Company in rush, cause of suffering (7)
I believe the answer is:
scourge
'cause of suffering' is the definition.
(I've seen this before)
'company in rush' is the wordplay.
'company' becomes 'co' (abbreviation).
'in' indicates putting letters inside.
'rush' becomes 'surge' (synonyms).
'co' going inside 'surge' is 'SCOURGE'.
(Other definitions for scourge that I've seen before include "Whip - bane" , "Person/thing causing great suffering; whip" , "source of evil" , "Pest" , "big nuisance" .)